About 25 percent of Amazon’s corporate workforce of some 382,000 employees is spread throughout a dozen or so research and development locations outside of its home in Seattle, according to sources familiar with the company’s tech spaces. Those operations tend to be in nondescript locations with little-to-no signage indicating Amazon’s presence, and rarely does the company grant interviews or answer to media inquiries when it comes to the often-secretive work underway at those locations.

But the company’s covert technology offices are perhaps the strongest indication as to where Amazon could be looking for HQ2 — a second North American headquarters that is expected to house up to 50,000 workers. Amazon has made clear that HQ2 will be located in a city with a talented workforce and world-class universities, a combination of resources that is abundant in all its R&D outposts.

Here’s a breakdown of some of Amazon’s biggest technology and research offices outside of Seattle.

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ABOUT THIS PROJECT: For the past nine months, The Business Journals and its 40 newsrooms have made a concerted effort to document the systematic expansion of Amazon.com Inc., from Class A office spaces in the nation's largest cities to former cornfields and barren industrial spaces long abandoned by industries of old. The company's growth, while massive in scope, has hinged on negotiations with local officials, deals with local real estate developers and tax breaks blessed by local municipalities. In short, it's all local. This project is both near-term and forward-looking in scope, and sets off to identify where this Seattle-based company's unrelenting expansion might be headed. It's as much about Amazon's end game as a business entity as it is about the long-lasting effect it is likely to have on America for decades to come.